Mel Gibson's ex-girlfriend Oksana Grigorieva has reportedly lost the settlement agreement she made following her split from the actor after violating a confidentiality agreement.

Grigorieva and Gibson became embroiled in a heated custody battle in 2011 which eventually resulted in the Lethal Weapon star agreeing to pay her $750,000 in instalments until 2016.

On Wednesday editors at TMZ.com reported that the Russian songwriter had filed for bankruptcy and now the website's writers claim the settlement agreement has also been revoked after she violated a gag order preventing her from discussing her time with the actor.

Court sources tell the website the violation relates to an interview Grigorieva gave with shock-jock Howard Stern in October, during which she described her relationship with Gibson as "painful and dark".

Her comments were allegedly enough for a judge to rule that she had violated the order, which prevents her from discussing her life with the actor, and she will not receive the remaining installments of her settlement, which are said to amount to $375,000.